BASIC SEPARATION THEORY
The actual separation of U F from U F in a gaseous diffusion plant is accomplished in the
converter. The converter, sometimes referred to as a diffuser, contains the barrier tubing
through which diffusion takes place. In the previous section we studied the flow through the
converter as a part of a stage. In this section we will see what takes place inside the converter.
In all, the entire cascade contains over 4000 converters -- one in each stage. The stage size
varies with the location in the cascade as shown in the table below.
Converter Stage Size vs. Location
185 or 215
90 or 105
Externally, the converter resembles a large cylindrical tank resting on its side (see Figure A-4).
There are openings at each end for the necessary piping connections. The outlet end of the
converter contains the "A" and "B" stream process gas outlets. The other end contains the
mixed process gas inlet and the stage coolant inlet and outlet. The cylindrical tank is called the
shell and is constructed of steel with welded joints. Its internal surface is nickel plated. There
are three external reinforcing flanges around the outside of the shell. The many hundreds of
barrier tubes, or tube bundles, contained in one converter are held in place by the spool, or
spool piece. The spool consists of struts and a central tube, or core, which is perforated and
allows part of the "A" stream leaving the barrier tubes to reach the converter outlet. On either
end of the core are tube sheets into the holes of which the barrier tubes are sealed by rolling or
swagging. Tube sheets are also mounted on the core between the end tube sheets to support
the barrier tubes.